Steering shaft u-joint coupling

February 21, 2016
Car steering system
Steering system.

The steering universal joint coupling, or simply steering u-joint, is a small but important part of the steering system. In most cars with an intermediate steering shaft, there are two u-joint couplings. The top u-joint connects the intermediate shaft to the steering column. The lower u-joint connects the intermediate shaft to the steering rack; see the diagram. To accommodate the steering tilt and telescope function, as well as for crash safety, the steering shaft must rotate at an angle.

The steering shaft u-joint must transfer the steering force from the steering wheel to the steering rack at an angle, without resistance or play. A faulty u-joint can cause looseness or seizing felt in the steering wheel. A vehicle with a bad steering u-joint is unsafe to drive.

Steering u-joint coupling problems

Bad steering u-joint
Bad steering u-joint: one of the needle
bearings in this u-joint is corroded.

The steering u-joint has four needle bearings packed with grease and sealed. It's a maintenance-free unit. In many cars, it can last for the lifetime of the vehicle. The most common problem with the steering u-joint is when the grease in one of the needle bearings dries out or when moisture causes corrosion (see the photo). In most cases, this problem happens to the lower steering shaft u-joint, as it's located inside the engine bay, see these photos fig 1, fig 2.

What are the symptoms of a bad steering u-joint? A failed steering u-joint can cause two types of problems: if the u-joint is seized, the steering may become stiffer or jam at certain angles. There could also be a popping or clunking noise while turning. If the steering u-joint is worn out or corroded, it will have some play. When driving, it feels that the steering is loose and you always have to correct it to keep the vehicle driving straight. See this video of a broken steering u-joint.

A worn-out steering u-joint can also cause a rattling noise in the steering when driving on rough roads. Of course these symptoms can also be caused by other problems in the steering system. A failed steering u-joint or other problems with the steering system make the vehicle UNSAFE. If you are experiencing these symptoms, have your vehicle checked out as soon as possible.

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Steering u-joint replacement

Steering u-joint
New lower steering u-joint coupling.

A failed steering u-joint coupling must be replaced. In some cars, it comes as a separate unit, in others it comes together with the intermediate steering shaft as an assembly. In an average car, the replacement of a separate lower steering u-joint costs from $160 to $320.

How easy is it to replace the steering u-joint? In most cars, it's not very difficult, although the u-joint is often seized on the shaft and might be difficult to remove. In some cars, it's important to mark the steering u-joint position on the steering rack shaft and the intermediate shaft splines, as the new u-joint must be positioned in the same way. In some cars, the u-joint must be replaced with the shaft. It's best to consult the service manual for the vehicle for the proper repair procedure.

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